I am not sure what exactly mid to late 20th century Russia did for the West

I think the significant thing is that there was an incredible lack of knowledge of anything that happened behind the "Iron Curtain" - and hardly anyone knew any Russian. The USSR was peopled exclusively by shadows and stereotypes. It still isn't a lot better, but at least you can learn Russian without immediately becoming suspicious.

Hard to replicate that sort of perspective for any other country, and even for any other time, I think. What slang/language would Burgess pick if he were writing the book now, I wonder?